You raise two points: one about the value of "loose coupling" between clients
and servers, and the other about the value of human-readable wire encodings.
I agree about the value of what you call "loose coupling". I think it is what
I've been calling "anarchic evolution". That is, independently developed
evolutionary changes to some existing application's network interfaces can be
concurrently and incrementally rolled out into a widely deployed existing
system. It's not quite correct to say that existing distributed system
technology cannot facilitate this. While some people will argue that subtyping
of object types suffices, I claim it doesn't do the job very well. Putting a
property list in every type you want to be extensible does the job, but not
very elegantly. I'm working on an idea I call signature extension that should
provide a more elegant solution. I don't have a decent introduction or
exposition ready yet, but you can find an out-take of a technical discussion of
the idea on the PDG home page (accessible to W3C members only).
On the binary-vs-text encoding issue, there is a lot of debate. There are
worthy pro's and con's on both sides. I myself favor modular software
architectures, enabling case-by-case selection of the best thing for the job at
hand.